CA2285255A1

CA2285255A1 - Composition and preparation method for water-in-oil emulstions for oil production

Info

Publication number: CA2285255A1
Application number: CA002285255A
Authority: CA
Inventors: Vyacheslav Nikolaevich Manyrin; Gennady Nikolaevich Pozdnyshev; Alexander Nikolaevich Dosov; Alexander Georgievich Savelyev
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-01-20
Filing date: 1998-12-21
Publication date: 1999-07-22
Also published as: RU2126082C1; WO1999036666A1

Abstract

The present invention pertains to the extraction of petroleum products and more precisely relates to compositions and methods for preparing water-in-oil emulsions. These emulsions can be used for adjusting the injectivity profile of injection wells and/or for isolating the water inflow in oil wells. In order to increase the kinetic and aggregative stability of the water-in-oil emulsions thus produced, this method comprises using as an emulsifier raw and heavy crude oil which contains gumming-asphalt, which has a high porphyrincomplex content of at least 100 .mu.g/g and which has not been submitted to any thermal-chemical treatment. The oily phase comprises a mixture of paraffinbased liquid hydrocarbons as well as a heavy solvent, wherein these components are selected in amounts by volume such that the (oily phase) mixture density is equal to that of the water used for preparing the water-in-oil emulsion.

Description

COMPOSITION AND PREPARATION METHOD FOR WATER-IN-OIL
EMULSIONS FOR OIL PRODUCTION
The invention is referred to oil production and namely, to compositions and methods of preparation of water-in-oil emulsions that are used to regulate injectivity profile and (or) block water inflow of producing wells.
The objective of the invention is to increase stability (aggregate and kinetic) of formed concentrated highly viscous water-in-oil emulsions through the application of stabilizers that are native (not subjected to any impact) polar surfactant metal (vanadium, nickel etc.) potphirine complexes and high molecular colloid dispersed asphaltene-resin oil components.
The role of aforementioned components in stabilizing water-oil emulsions formed at production and treatment of oil is well known and reviewed in detail in [1].
There is a known method of preparing oil concentrates of water-in-oil emulsions [2] that involves dissolving the asphaltenes or petroleum products containing them in aromatic hydrocarbons. Besides asphaltenes tar can be used. To prepare a working water-in-oil emulsion water is slowly added to the oil concentrate at intensive stirring.
Volume ratio of the emulsion phases is between 1:9 and 9:1 (depending on the composition and operational requirements). However, it is known that in the process of oil refining many highly active polar components for example, porphirins, are eligible to destruction (thermal destruction), and dissolving ability of asphaltene-resin oil components decreases (even in aromatic hydrocarbons) which negatively impacts their emulsifying properties.
Asphaltenes emulsify water well in their colloid (highly dispersed) state.
This state is determined by the optimum ratio of aromatic hydrocarbons (dissolving asphaltenes) and aliphatic hydrocarbons (in which asphaltenes practically do not dissolve) in the oil phase.
Deviation form the optimum ratio in the hydrocarbon composition of the oil phase leads to larger asphaltene particles or their complete dissolving. In both cases effectiveness of their stabilizing ability drops.
In the method of preparation of water-in-oil emulsions for agricultural purposes [3]
selected as a prototype it is proposed to use emulsifiers - natural stabilizers of field oil emulsions separated prior from the so called "intermediary layer" formed in oil tanks (for example, through a centrifuge). Separated concentrate of the water-in-oil emulsion is destructed through boiling in water, they are then washed through a filter to remove salts and demulsifier traces and resulting powder product is used as a stabilizer of water-in-oil emulsions. Research [4] determined that the composition of stabilizers extracted from field oil emulsions of most pools contains 50-80 %(mass) of highly fusible paraffin-ceresin hydrocarbons, 10-70% of asphaltene-resin components and the remaining portion is represented by inorganic colloid dispersed particles of various mechanical impurities among which the major role in raising stability of field emulsions belongs to iron sulphide [5]. Since the process of extraction of natural stabilizers from emulsions involves boiling and prolonged contact of the product with air oxygen and water the major surfactant stabilizers of oil emulsions - metal-porphirine complexes lost their properties due to destruction. This is a major disadvantage of the method.
Besides, to provide good dissolving of "paraffin" emulsifiers of water-in-oil emulsions in the oil phase a considerable amount of intensifying additive (i.e. up to 30-40% (mass) of butyl ether) was introduced into the oil phase. Such "paraffin" stabilizers can not provide stability of water-in-oil emulsions at temperature above melting temperature of contained in their composition paraffin-ceresine components.
According to information [4] most "paraffin" stabilizers can not form stable concentrated water-in-oil emulsions at 60-80°C. It is also known from experience that when producing oil at certain fields concentrated water-in-oil emulsions are formed that do not destruct at temperatures even around +100°C without treating them with a demulsifier and additional impact of such dehydrating factors as electric or centrifugal force. Such stable water-in-oil emulsions as a rule form oil with abnormally high content of metal-porphirin and asphaltene-resin components. Emulsified water shows increased content of colloid suspension of iron sulphide (for various reasons).
In the present invention to reach the established objective it is proposed to use a composition containing "crude" not treated in any way heavy asphaltene-resin oil with high (no less than 100 p,kg/g) metal-porphirin complex as an emulsifying component to prepare highly stable concentrated highly viscous water-in-oil emulsions. It is proposed to use aromatic hydrocarbon (toluene, xylol etc) as a solvent. Depending on the properties (density, viscosity) and quantitative content of metal-porphirin complexes, asphaltenes, resin and emulsified water (present in oil as a ballast and not participating in calculations of the composition. Water has to be removed from the composition later after it is prepared through settling) in crude oil the emulsifying component and solvent content in the composition can vary within (% of mass):
Crude oil 25-85 Solvent 15-75 To prepare stable viscous water-in-oil emulsions to regulate injectivity it is required first to prepare a corresponding "oil" phase in the field. Within 5-25% (miss) of the aforementioned composition shall be added to the oil phase as an emulsifier.
As the oil phase it is proposed to use the most available (and economical) for each pool liquid oil hydrocarbons of the paraffin hydrocarbons such as LPG (liquefied petroleum gas), unstable gas benzene etc. blended with "AFK" agent (TU 212-199-05763458-94) that serves the function of an effective solvent of asphaltene-resin and porphirin oil components and regulator of the "oil" phase density.
The optimum ratio of blended volumes of the aforementioned components of the "oil phase" is such at which the density of resulting blend ("oil phase's shall equal the density of water used to prepare emulsions.
After the aforementioned composition as an emulsifier is added to the "oil"
phase the density of which is regulated intense dispersion of water in "oil" takes places through any common method (for example, with a blender or circulating the system through a pump).

A specific volume of water that has to be emulsified in the specific volume of "oil"
should be added gradually in small portions.
Example 1. To prepare water-in-oil emulsion a composition was used that contained unique in its porphirin component (Table 1 ) heavy asphaltene-resin oil from Verkhozimski oil production division of '2'enzaneft" and toh~ene in a 3:1 ratio. As an "oil" phase a blend of low octane number gasoline (specific weight - 710 kglm3) and APK (specific weight - 1,500 kg/m3) was used at a 1:1 ratio. The density of resulting "oil" phase was 1.105 kg/m3. This corresponded to the density of salt produced water used to emulsify water in the "oil". Following these conditions (no differential in density of emulsified "oil" and water phase) ideal terms are created to provide 100%
kinetic stability of resulted water-in-oil emulsion. This does not exist in any known method of preparation of similar emulsions.
The content of emulsifier in the "oiI" phase in both available method [3]
selected as a prototype and the proposed composition and preparation method for water-in-oil emulsions for oil production was changed within 1 to 30% of mass. In both cases kinetic (K,) and aggregate (A,) stability of formed water-in-oil emulsions was evaluated.
I~" was evaluated based on the volume of separated "oil phase" (Vo; % of volume) of the initial volume of the "oil phase" (V~) that was used to prepare a 50% water-in-oil emulsions in standard conditions after its static settling within 24 hours at temperature of 20°C, i.e.
~ _ [(V~-V°~°~] x 100 ( 1 ) Ao was evaluated based on the separated water (V°, % of volume) of the initial water volume (V;) that was used to prepare a 50% water-in-oil emulsions with the same dehydrating factors, such as treatment in the centrifugal field at 20°C
within t = 5 minutes and 6 = 3,000 RPMs, i.e.
~. _ [(V.-V°)~~] x 100 (2) Table 2 contains major technical parameters of 50% water-in-oil emulsions (viscosity, kinetic and aggregate stability) that determine their effective application for oil production. Based on this data the proposed composition and preparation method for water-in-oil emulsions allows to form more viscous, kinetically and aggregately more stable water-in-oil emulsions with 1.5-3 times less volume of components compared to available compositions and methods.

Table 1 Physical-chemical parameters of Verkhozimski oil Description Value Densit at 20C 939 Molecular wei ht 350 Kinematic viscosit at 50C mm2/sec 83.58 Tem ature of solidi in , C -22 Acid number m HOIVh 0.06 Colon ca acit , % of mass g.g Composition, % of mass Asphaltenes 10.0 Silica gel resins 22.5 Paraffin, /tC of melting 4.95/54 Total sulfur 2.75 Vanadium, pkg/g 75.0 Nickel, p,kg/g 27.0 Table 2 Properties of water-in-oil emulsions # Method of Volume Pro erties of of 50%
water-in-oil emulsions preparation emulsifierViscosityStabilit mPa-sec Kinetic Aggregate Proposed 1.0 670 95 70 Available 1.0 105 15 10 Proposed 2.5 835 95 85 Available 2.5 127 30 30 Proposed 5.0 270 98 90 Available 5.0 205 35 45 Proposed 10 1,050 100 95 Available 10 320 50 75 Proposed 15 1,270 100 100 Available 15 410 65 90 Proposed ~ 20 1,390 100 100 Available 20 510 70 95 Proposed 25 1,470 100 100 Available 25 670 85 100 Proposed 30 1,500 _ 100 Available 30 850 100 100 REFERENCES
I. G.N. Pozdnyshev "Stabilization and Destruction of Oil Emulsions", M., "Nedra", 1982, page 221 2. Patent USSR # 245259, published Bulletin #19, 1969.

3. Patent USSR # 318381, published Bulletin #32, 1971.

4. G.N Pozdnyshev, A. A. Petrov "Natural Stabilizers and Stability of Oil Emulsions", TatNIPIneft, issue XIX, Kuibyshev, 1971, page 124.

5. A.A. Petrov, S.I. Borisov, "Allowable Limits of Blending Hydrogen Sulphide and Sulfur Containing Water-Oil Emulsions in Oilfield Oil Separation". "Oil Industry"
magazine, # 11, 1979, page 38-40.
COMPOSITION AND PREPARATION METHOD FOR WATER-IN-OIL
EMULSIONS FOR OIL PRODUCTION
Invention formats.
1. The composition of water-in-oil emulsions for oil production containing the oil phase, water, emulsifier (contains emulsifying component and solvent) is distinct due to the fact that as the emulsifying component is crude heavy asphaltene-resin oil with a high, no less than 100 lakglg content of metal-porphirine components. The solvent is an aromatic hydrocarbon - toluene, xylol. The composition is (% of mass): 25-85 of heavy oil, 15-75 of solvent. The oil phase is liquid oil hydrocarbons of the paraffin series blended with APK solvent of asphaltene-resin and paraffin oil components. The ratio is such that the oil phase density equals the density of water used to prepare water-in-oil emulsions.
2. The composition, as per paragraph 1 is distinct due to the fact that it contains an emulsifier of the aforementioned composition in the volume of 15-25% of mass.
3. The method of preparation of water-in-oil emulsions for oil production involves adding the emulsifier into the oil phase and dispersion of water in formed oil. The method is distinct due to the fact that the emulsifier added to previously prepared to that oil phase is a composition containing crude heavy asphaltene-resin oil as the emulsifying component. The content of metal-porphirine complexes in oil is high, no less than 100 p,kg/g. The volume of metal-porphirine complexes is 25-85% of mass.
An aromatic hydrocarbon - toluene, xylol is a solvent of the composition -at 15-75%
of mass. Liquid oil hydrocarbons of the paraffin series blended with APK
solvent of asphaltene-resin and paraffin oil components are used as the oil phase. The ratio of liquid oil hydrocarbons and APK solvent is such that the density of the oil phase is equal to the density of water used to prepare water-in-oil emulsions.
4. The method as per paragraph 3 is distinct due to the fact that the emulsifier of the aforementioned composition is added at S-25 % of mass.

Claims

Here is what we claim:

1. Composition of a reverse emulsion for oil production, including the oily phase, water, emulsifier with emulsion component and solvent, containing, as an emulsifying agent, heavy crude asphalt-waxy oil with high (not less than 100 Mkg/g) metal-porfirine contents as a solvent they use aromatic hydrocarbon - toluene, xylene - having the following per cent by weight content of the a.m. components a.m.
crude oil - 25- 85, a.m. solvent -15 - 75; as au oily phase they use liquid petroleum hydrocarbons of paraffin row in mixture with APK-solvent for asphalt-waxy and parafine components in oil, in ratio, when the density of the oily phase is equal to the density of water, used for make-up of the reverse emulsions.

2. Composition as pes Claim 1, differing in the fact, that it contains the emulsifier of the a.m. composition in amount of 15 - 25 % wt.

3. Procedure to make up the reverse emulsions to be used is oil production, including the addition of emulsifier into oily phase and the dispersion of water in the resulted oil, differing in the fact, that in the pre-treated oily phase, where the liquid petroleum hydrocarbons of paraffin row are used in a mixture with APK-solvent for asphalt-waxy and porfirine components in oil, in ratio, when the density of the oily phase, is equal to the density of water; then they add, like the emulsifier, the composition, containing, as an emulsifying agent, crude heavy asphalt-waxy oil with high (not less than 100 Mkg/g) metal-porfirine content in amount of 25 - 85 % by weight and as a solvent - aromatic hydrocarbon - toluene, xylene - in amount of 15 - 75 % wt.

4. Procedure as per Claim # 3, differing in the fact, that the emulsifier of the a.m. composition is added in amount of 5 - 25 % wt.